Pseudomonas aeruginosa cytotoxin: the Asp197-Gly-Asp-Tyr-His-Tyr-His-Tyr202 containing loop is critical for plasma membrane binding

The cytotoxin from Pseudomonas aeruginosa is a pore-forming toxin that binds specifically to water channel-related molecules of the erythrocyte membrane. Here, we have defined a domain, Asp¹⁹⁷-Gly-Asp-Tyr-His-Tyr²⁰² of the cytotoxin, to be essential for receptor binding. Cytotoxin point mutants from the recombinant gene carrying substitutions in the domain were characterized in terms of inhibiting the binding of radioiodinated natural cytotoxin to rat erythrocyte and producing cytotoxic effects in human granulocytes. A synthetic peptide representing residues 191–211 of the cytotoxin acted as a competitive inhibitor at a concentration of 10^–5 M. In contrast, two other cytotoxin-specific peptides were inactive. Structure prediction of the binding sequence shows a loop structure with similarities to the sequence around His³³² in Aeromonas aerolysin essential to receptor binding.     

Permeability changes of Ehrlich mouse ascites tumor cells induced by a cytotoxin from Pseudomonas aeruginosa

Summary Ehrlich ascites tumor cells from mice were damaged during in vitro incubation with a cytotoxin from Pseudomonas aeruginosa at concentrations of>1 g/ml. After a short time the cells started to lose potassium whereas their sodium content increased. When the protein concentration of the incubation medium was adjusted to the protein concentration inside the cells, swelling and release of glucose-6-phosphate dehydrogenase was avoided. However, lysis of the cells still took place.Preincubation of cells with tetrodotoxin, 4-aminopyridine or tetraethylammonium did not influence damage to the cells. The cells showed a steep increase in toxin response between 17° and 27°C ranging from insensitivity to full sensitivity.An increase in electrical conductance was measured during incubation of cholesterol bilayer membranes with a cytotoxin concentration of 1 g/ml. The conductance was increased by a factor of ten within 30 min at 25°C which indicates the involvement of membrane lipids in the cytotoxin action.Part of this study has been presented at the Joint Meeting of the Scandinavian and German Pharmacological Societies, Lübeck (Grieshaber and Lutz 1980)     

Cytotoxin and hemolysin in diseased fish during epidemic outbreaks

Outbreaks of fish diseases have been reported in many parts of the world. The outbreaks are difficult to control. During December 1982 and March 1983, there were severe outbreaks of fish disease in Thailand. A study on the presence and inactivation of harmful toxins, i.e., cytotoxin and hemolysin, by heat, salt and gastric pH was undertaken. Cytotoxin and hemolysin were detected in all diseased snakehead fish (Ophicephalus striatus) homogenates. Aeromonas hydrophila F 588 isolated from the diseased snakehead fish also produced cytotoxin and hemolysin. No detectable cytotoxic or hemolytic activity was found in the fish homogenates or A. hydrophila F 588 cell suspensions after heating at 100°C for 5 minutes or autoclaving at 121°C for 15 minutes at 15 lb/in.² Cytotoxic activity remained positive in all concentrations (0% to 30% W/V) of NaCl. However, no cytotoxin could be detected when the pH of the samples was 2.0. There was a 55% decrease in hemolytic activity when A. hydrophila F 588 was incubated in 30% NaCl for 1 month at 30°C. Furthermore, there was a 50% decrease in the activity when the pH of the samples was 2.0. Hence, the diseased fish is safe for consumption if it is heated for 5 minutes at 100°C. However, it is unsafe to consume unheated salt-fermented fish.     

Interaction ofPseudomonas aeruginosa cytotoxin with plasma membranes from Ehrlich ascites tumor cells

Summary Biologically active¹²⁵I-cytotoxin fromPseudomonas aeruginosa binds to plasma membranes from Ehrlich ascites tumor cells in a saturable manner. The Scatchard plot indicated a single binding site with a capacity of 260 pmoles/mg of membrane protein and aK _D of 2×10^–8 M. Specific binding was dependent on temperature, pH and ionic strength. Thus constant levels of bound¹²⁵I-cytotoxin were attained either within 30 min at 30°C or within 3 h at 4°C. Binding was 30-fold higher at 4°C vs 30°C and 2-6-fold higher at pH 5.3 vs pH 8.3. Binding was not effected by 50 mM sugar or sialic acid. 300 mM sucrose, however, instead of phosphate buffer, reduced binding by 50%. Pretreatment of plasma membranes with trypsin or papain led to a significant decrease in¹²⁵I-cytotoxin binding. A pretreatment with phospholipase C or D had no effect, whereas phospholipase A₂ induced a decrease by 34%. The collected data suggest that the binding site for¹²⁵I-cytotoxin within the plasma membrane from Ehrlich ascites tumor cells is a membrane protein.Correlation of¹²⁵I-cytotoxin binding and membrane action of the unlabelled cytotoxin can be observed through (a) increased lowering of the cellular K⁺ and Na⁺ gradient by decrease of medium pH, (b) decreased toxicity after substitution of ions by sugar, and (c) increased breakdown of cellular cationic gradient after temperature shift from 4°C to 37°C.     

Toxic effect and adaptation in Scenedesmus intermedius to anthropogenic chloramphenicol contamination: genetic versus physiological mechanisms to rapid acquisition of xenobiotic resistance

Anthropogenic water pollution is producing a challenge to the survival of phytoplankton populations. From an ecological point of view, the tolerance of these microorganisms to water pollution is of paramount importance since they are the principal primary producers of aquatic ecosystems. The adaptation of a common chlorophyta species (Scenedesmus intermedius) exposed to selected dose-response chloramphenicol (CAP) concentrations has been analyzed. A fluctuation analysis demonstrated that CAP-resistant cells arise due to spontaneous mutation which occurs randomly prior to the antibiotic exposure. CAP-inhibited growth and photosynthetic performance of algal cells at 0.28 mg/l, and the IC₅₀₍₇₂₎ value was established in 0.10 mg/l for both parameters. The mutation rate from CAP sensitivity to resistance was 1.01 × 10⁻⁵ mutations per cell division, while the frequency of CAP-resistant allele in non-polluted environment was estimated to be 5.5 CAP-resistant mutants per 10³ sensitive-cells. These results demonstrate that resistant mutants exhibit a diminished fitness until 5 mg/l of CAP, thus enabling the survival of microalgae population.     

中红外光谱法评价6家企业生产的黄柏、茯苓和熟地黄配方颗粒的质量

目的 用中红外光谱技术对6家企业生产的黄柏、茯苓及熟地黄3种配方颗粒进行质量考察,分析了不同企业配方颗粒的一致性。方法 以峰位、峰形、相对峰强度或主要标准峰个数等为考察指标,对不同企业生产的同一品种的配方颗粒与标准药材及自制提取物的谱图进行对比,分析三者之间的差异（相似度）。结果 6家企业的黄柏配方颗粒在1 604、1 507 cm^-1处特征峰的相对峰高的变化不同,其原药材质量可能存在差异;茯苓配方颗粒因采用辅料种类不一,中红外光谱图差异明显;熟地黄配方颗粒因原药材投料比不同,随着辅料含量的增加,与熟地黄提取物的相关系数降低。结论 中红外光谱具有操作简单、快速、专属性强、不需要对样品进行分离等优点,尤其是揭示不同企业的同一种配方颗粒因采用原药材的品质、辅料不同等因素所造成质量差异,因此,中红外光谱技术为保证配方颗粒的均一性提供了客观的分析手段和数据支撑。     

Relationship between mucosal levels of interleukin 8 and toxinogenicity of Helicobacter pylori

Aim of study: To investigate if an association exists between in-vivo mucosal levels of IL-8 and bacterial expression of cytotoxin and cagA gene of H. pylori. Methods: Seventy-two dyspeptic patients referred for endoscopy were studied, including 36 patients with peptic ulcer (PU) and 36 with non-ulcer dyspepsia (NUD). Biopsies were taken for histology, H. pylori culture and measurement of IL-8 by ELISA. To test the ability of H. pylori to produce cytotoxin (VacA), broth culture supernatants were assayed on Vero cells and vacuolation measured. PCR was used to detect the cagA gene of H. pylori. Results: H. pylori was isolated in 52 of 72 patients studied. Among the 52 strains, 25 (49%) were VacA+ve/cagA+ve; 12 (23%) were VacA−ve/cagA−ve; the remaining 15 strains (28%) were either VacA+ve/cagA−ve or VacA−ve/cagA+ve. IL-8 levels (median (interquartile) pg/mg) in patients infected with VacA+ve (1.5 (0.64, 2.84)) or cagA+ve strains (1.25 (0.72, 2.34) were significantly higher than in those with VacA−ve (0.76 (0.4, 1.0)) or cagA−ve strains (0.5 (0.4, 1.5); p<0.05). The neutrophil infiltration score was also higher in patients infected with VacA+ve or cagA+ve strains than in those infected with VacA−ve or cagA−ve strains (p<0.05). Conclusion: VacA+ve/cagA+ve strains were associated with an enhanced production of mucosal IL-8 in vivo and correlated with a stronger infiltration of neutrophils. Enhanced mucosal production of IL-8 and its role in neutrophil chemotaxis and activation could be important in H. pylori-induced gastroduodenal inflammation and in the development of peptic ulcer disease.     

Lipopolyamine-Mediated Single Nanoparticle Formation of Calf Thymus DNA Analyzed by Fluorescence Correlation Spectroscopy

Purpose The aim of this study is to analyze linear calf thymus DNA (ct DNA) nanoparticle formation with N⁴,N⁹-dioleoylspermine and N¹-cholesteryl spermine carbamate. Methods Fluorescence correlation spectroscopy (FCS) was used to determine the quality of ct DNA condensed by lipopolyamines. ct DNA was prelabeled with PicoGreen (PG) to allow fluorescence intensity fluctuation measurement and analysis. Results N⁴,N⁹-Dioleoylspermine efficiently condensed ct DNA into point-like molecules with diffusion coefficient (D) = 1.8 × 10⁻¹² m²/s and particle number (PN) = 0.7 [at ammonium/phosphate (N/P) charge ratio=1.0–1.5]. The determined PN values are close to the theoretical value of 0.6, providing evidence that the DNA conformation has been fully transformed, and thus a single nanoparticle has been detected. N¹-Cholesteryl spermine carbamate showed (slightly) poorer DNA condensation efficiency, even at higher N/P ratios (N/P = 1.5–2.5) with D = 1.3 × 10⁻¹² m²/s and PN value of 5.2. N⁴,N⁹-Dioleoylspermine is a more efficient DNA-condensing agent than N¹-cholesteryl spermine carbamate. Conclusions FCS measurement using PG as the probe is a novel analytical method to detect single nanoparticles of condensed DNA in nonviral gene therapy formulation studies.     

Functional significance of the highly conserved Glu in the putative pore-forming helix 3 of the Bordetella pertussis haemolysin toxin

Adenylate cyclase-haemolysin toxin (CyaA) is a virulence factor secreted from the etiologic agent of whooping cough, Bordetella pertussis. Previously, the haemolysin or pore-forming domain (CyaA-PF) has been shown to cause cell lysis of sheep erythrocytes independently, and the predicted helix 3_(570−593) within the PF-hydrophobic stretch could be a pore-lining constituent. Here, a plausible involvement in haemolytic activity of polar or charged residues (Glu⁵⁷⁰, Gln⁵⁷⁴, Glu⁵⁸¹, Ser⁵⁸⁴ and Ser⁵⁸⁵) lining the hydrophilic side of CyaA-PF helix 3 was investigated via single-alanine substitutions. All the 126-kDa mutant proteins over-expressed in Escherichia coli were verified for toxin acylation as the results are corresponding to the wild-type toxin. When haemolytic activity of E. coli lysates containing soluble mutant proteins was tested against sheep erythrocytes, the importance of Glu⁵⁷⁰, which is highly conserved among the pore-forming RTX cytotoxin family, was revealed for pore formation, conceivably for a general pore-lining residue involved in ion conduction.     

hOGG1 SER326CYS genetic polymorphism in a Turkish population

Oxidative DNA damage, caused by either endogenous or exogenous sources of reactive oxygen species (ROS), has been linked to aging, chronic degenerative diseases, inflammatory diseases and cancers. 8-Hydroxydeoxyguanine (8-OHdG) is a major lesion produced by ROS. Among various types of DNA base modifications, 8-OHdG has been the most widely studied and is considered a key biomarker of oxidative DNA damage. Human 8-oxoguanine DNA glycosylase 1 (hOGG1) is a key component of the base excision repair (BER) pathway and catalyzes the removal of 8-OHdG. Ethnic and inter-individual differences in hOGG1 activity and several kinds of polymorphisms at the hOOG1 gene locus have been observed in the different populations studied so far. Since no information is available on the inter-individual variability of the hOGG1 genotype in the Turkish population, we genotyped 206 healthy, unrelated Turkish individuals. The allelic frequencies of the hOGG1 gene in the Turkish population were found to be 0.50, 0.41 and 0.09 (Ser/Ser, Ser/Cys and Cys/Cys, respectively). Our results are similar to those for Caucasians studied previously but are different from Asian populations. It seems that there is a growing need for extensive genotype studies with respect to the hOGG1 gene due to its importance to various types of cancer and to smoking habits.     

Isolation and identification of the toxic peptides from Lophyrotoma zonalis (Pergidae) sawfly larvae

The broad-leaved paper bark tree Melaleuca quinquenervia (Cav) (Myrtaceae) was introduced into Florida (USA) early in this century it has proliferated to such an extent that urgent measures are now required to control it. The sawfly Lophyrotoma zonalis (Pergidae) has been introduced as a possible biological control agent due to its ability to defoliate M. quinquenervia. Because toxic D-amino acid- containing peptides have been isolated from some sawfly species, L. zonalis larvae were processed using the previously reported method for the recovery of these compounds. The toxins lophyrotomin (as the free C-terminal acid) and a mixture of pergidin and Val ⁴-pergidin were isolated at 0.36 and 0.43% yield of the dried larvae, respectively. Both compounds when dosed intraperitoneally to C57/Bl6 male mice were hepatotoxic with lowest lethal doses of 8 and 32 mg/kg, respectively. The pathology of the liver was different for each compound, with the lophyrotomin free acid causing a periportal haemorrhagic necrosis and the pergidin causing a periacinar coagulative necrosis.     

多色探针熔解曲线法在卡马西平不良反应相关基因检测中的临床评价

目的 对多色探针熔解曲线法（multicolor melting curve analysis,MMCA）用于卡马西平不良反应相关的HLA-B^*15：02基因检测进行临床评价。方法 收集厦门市中心血站1 147份厦门地区无偿献血者的外周静脉血样本,经基因DNA提取后,按双盲对照试验,分别应用MMCA法和HLA-SBT测序法对各样本进行HLA-B^*15：02基因检测,比较2种检测方法的符合率。对于检测结果不一致的标本,采用第三方Sanger测序和电泳验证,计算总符合率。结果 采用MMCA法共检出77份HLA-B^*15：02阳性标本,1 070份HLA-B^*15：02阴性标本。采用HLA-SBT测序法共检出74份HLA-B^*15：02阳性标本,1 070份HLA-B^*15：02阴性标本,以及3份无明确的分型信息的标本（仅显示为B^*15：VG-B^*15：CYS型）。该3份标本经Sanger测序以及电泳验证,确认为HLA-B^*15：02阳性标本。因此,MMCA法检测HLA-B^*15：02基因的阳性检出率为100%（77/77）,阴性检出率为100%（1 070/1 070）,总符合率为100%（1 147/1 147）。此外,在1 147份临床标本中共检出77份阳性结果,HLA-B^*15：02的携带率为6.7%（77/1147）,这与文献报道的数据基本一致。结论 MMCA法用于HLA-B^*15：02基因的检测,具有简便、快速、灵敏度高、特异性强等优点,可应用于卡马西平不良反应相关的HLA-B^*15：02基因的临床辅助检测。     

Is Helicobacter pylori seropositivity related to body mass index in the United States?

Background: Helicobacter pylori infection may decrease serum ghrelin and increase gastric leptin levels, which may, in turn, decrease body mass index. Aim: To determine whether H. pylori seropositivity is associated with body mass index. Methods: Serum H. pylori and cytotoxin‐associated gene product A (CagA) antibody levels were measured on 6724 adult participants of the third National Health and Nutrition Examination Survey (1988–91). We evaluated the association between H. pylori/CagA antibody status [both negative (?/?), H. pylori‐positive/CagA‐negative (+/?), or both positive (+/+)] and body mass index, adjusting for sociodemographic factors. We also investigated whether H. pylori/cytotoxin‐associated gene product A antibody status was associated with fasting serum leptin levels. Results: H. pylori/CagA antibody status was not associated with obesity (body mass index ≥ 30 kg/m²) [adjusted odds ratio (OR) 1.2, 95% CI: 0.9–1.6 comparing (+/+) to (?/?) and adjusted OR 1.1, 95% CI: 0.8–1.5 comparing (+/?) to (?/?)], overweight (body mass index 25 to <30 kg/m²) [adjusted OR 1.0, 95% CI: 0.7–1.2 comparing (+/+) to (?/?) and adjusted OR 1.0, 95% CI: 0.8–1.3 comparing (+/?) to (?/?)], or fasting serum leptin level in the USA population. Conclusions: H. pylori seropositivity and CagA antibody status are not associated with body mass index or fasting serum leptin level.     

The genetic epidemiology of melanocortin 4 receptor variants

While rare MC4R mutations are the commonest cause of monogenic forms of extreme, early-onset obesity, growing evidence shows that common MC4R variants contribute to obesity in the general population. Candidate gene studies have focussed on the V103I and I251L MC4R variants that both affect MC₄ receptor function in vitro. Individual association studies, which are typically small and underpowered, have found no association between V103I (frequency of 103I-allele: ~ 4%) or I251L (251 L-allele: ~ 2%) and the risk of obesity in the general population. However, large-scale meta-analyses have confirmed that both variants reduce the risk of obesity by − 21% in 103I-allele carriers (P < 10⁻⁴) and by − 50% in 251 L-allele carriers (P < 10⁻⁴). Recently, genome-wide association studies have identified a common variant (minor allele frequency: ~ 27%) at ~ 188 kb downstream of MC4R showing robust association (P < 5 × 10⁻⁸) with BMI and obesity in adults and children. Each additional minor allele increases BMI by 0.20 kg/m², body weight by 700–1000 g, and obesity risk by 14% in adults. Interestingly, this variant also showed association with increased height, consistent with the phenotype seen for rare MC4R mutations. Although MC4R is the nearest gene and phenotypic associations are consistent with those of MC4R mutations, it has not yet been established whether this variant indeed reflects MC₄ receptor function. Taken together, common MC4R variants contribute to variation in BMI and obesity risk in the general population. Of particular interest is the finding from genome-wide association studies that suggests that the region downstream of MC4R contributes to its regulation.     

Effect of filamentation and mode of growth on antifungal susceptibility of Candida albicans

Biofilm formation involving profuse hyphal growth is a major characteristic of Candida spp. and confers higher antifungal resistance than its planktonic mode of growth. We investigated the antifungal susceptibility of Candida albicans and its hyphal mutants (Δefg1/efg1, Δcph1/cph1 and ΔΔcph1/cph1 efg1/efg1) to commonly used antifungals during planktonic, adhesion and biofilm modes of growth. The minimum inhibitory concentration (MIC) of each antifungal agent was determined for a lower inoculum (1 × 10³ cells/mL) and higher inoculum (1 × 10⁷ cells/mL) of planktonic Candida. Furthermore, MICs of C. albicans biofilms and adhesion modes of growth were determined with a standard XTT assay. Candida albicans in adhesion and biofilm modes of growth, but not in planktonic mode, were resistant to all five antifungal agents tested. Although Δefg1/efg1 and ΔΔcph1/cph1 efg1/efg1 mutants formed less biofilm than wild-type C. albicans SC5314, they were similarly resistant to caspofungin. However, these mutants were more sensitive to amphotericin B and nystatin than the wild-type. Adhesion per se confers increased resistance to antifungal agents, which is further pronounced in the biofilm mode of Candida. Filamentation does not appear to be a major determinant of the antifungal resistance in Candida biofilms.     

大鼠和小鼠Pig-a基因突变试验历史背景数据采集

目的 介绍大鼠及小鼠 Pig-a基因突变试验方法,并汇总国家药物安全评价监测中心 2015—2022年开展的基于免疫磁珠检测法的大鼠及小鼠 Pig-a 基因突变试验背景数据。方法 阴性物质包括超纯水和 0.5% 羧甲基纤维素钠（CMCNa）,雄性 C57BL/6J 小鼠间隔 24 h ig 0.5% CMC-Na,连续 7 d;雄性 SD 大鼠间隔 24 h ig 0.5% CMC-Na,连续 14 d;大鼠间隔24 h ig 超纯水,连续 3 d。阳性对照为已知致细菌突变化合物,包括 N-乙基-N-亚硝基脲（ENU,10、40 mg·kg^-1）、盐酸丙卡巴肼（PCZ,60、150 mg·kg^-1）、乌拉坦（EC,300、800 mg·kg^-1）、N- 亚硝基二甲胺（NDMA ,1.5 mg·kg^-1）、N- 亚硝基二乙胺（NDEA,15 mg·kg^-1）。小鼠间隔 24 h ig ENU 40 mg·kg^-1,连续 3 d;间隔 24 h ig NDMA 1.5 mg·kg^-1、NDEA 15 mg·kg^-1,连续 7 d。大鼠间隔 24 h ig PCZ 150 mg·kg^-1、EC 800 mg·kg^-1、ENU 40 mg·kg^-1,连续 3 d ;间隔 24 h ig PCZ 60 mg·kg^-1、EC300 mg·kg^-1、ENU 10 mg·kg^-1,连续28 d。分别于给予受试物前,首次给予后14、28 d采集外周血,用流式细胞术检测大鼠红细胞表面 CD59蛋白的结合情况,结合免疫磁性计数微球技术计算网织红细胞（RETs）占总红细胞的百分率（%RET）（作为外周血毒性考察指标）、总红细胞中CD59表达为阴性细胞（RBC^CD59-,即突变的总红细胞）发生率和RETs中CD59表达为阴性细胞（RET^CD59-,即突变的 RETs）发生率。结果 各试验%RET数值均无大幅增加。SD大鼠和 C57BL/6J 小鼠的阴性对照组RBC^CD59-和 RET^CD59-突变率均低于 5×10-6,小鼠的背景值相对不稳定。连续 3 d ig给予小鼠 40 mg·kg^-1的 ENU,RBC^CD59-和RET^CD59-发生率自给药后2周开始均大幅增加（P＜0.05）,给药后4周进一步增加（P＜0.01、0.001）;给予小鼠NDMA后2、4周,RBC^CD59-发生率略有增加,但仍在阴性背景范围内,但RET^CD59-发生率在给药后第2周大幅增加（P＜0.001）,给药后第4周则大幅回落;给予小鼠NDEA后2周,RBC^CD59-和RET^CD59-发生率均有所增加（P＜0.05、0.001）,给药后第 4 周则有所降低。连续3 d ig给予大鼠40 mg·kg^-1 ENU,或连续28 d ig给予大鼠10 mg·kg^-1 ENU,RBC^CD59-、RET^CD59-发生率自给药后第2周开始均大幅增加（P＜0.001）,给药后第 4 周进一步增加（P＜0.001）;连续 3、28 d ig 给予大鼠不同剂量的 PCZ 或 EC 后,RBC^CD59-和RET^CD59-发生率的变化趋势与 ENU类似,但 EC诱发的突变细胞率低于 ENU和 PCZ。结论 体内 Pig-a基因突变试验可在首次给药后4周内有效检出致细菌突变化合物ENU、PCZ、EC、NDMA、NDEA的致突变性。提供了大鼠和小鼠Pig-a基因突变试验的背景值范围,为标准化试验方法的建立和研究结果的判定提供借鉴。     

Acute toxicity and cytotoxicity of Bacillus thuringiensis and Bacillus sphaericus strains on fish and mouse bone marrow

The insecticidal properties of delta-endotoxins from Bacillus thuringiensis (Bt) serotypes kurstaki and israelensis and crystal proteins of Bacillus sphaericus (Bs) serotype H5 have been used in insect control for decades. The availability of microbial toxins in biopesticides as well as in plants with incorporated protection has been increasing the concerns about biosafety. Acute toxicity to Danio rerio and cytotoxicity on mouse bone marrow cells and peripheral erythrocytes of Oreochromis niloticus were tested with Bt israelensis, Bt kurstaki and Bs H5 strains. The concentration and dose tested were 10⁶ and 10⁸ spores/ml, respectively. Neither lethality nor effects on mouse bone marrow were promoted by any strain. In necrosis–apoptosis study on peripheral erythrocytes of O. niloticus an increased frequency of necrotic cells caused by exposure to strains of B. thuringiensis was found. Exposure to B. sphaericus did not show cytotoxic effects in either tested system. None of the strains studied induced apoptosis in contrast with the chemical controls.     

丝瓜叶中丝瓜皂甙O的化学结构研究

丝瓜叶中丝瓜皂甙Ｏ的化学结构研究梁龙，鲁灵恩，蔡元聪（四川省中药研究所重庆６３００６５）丝瓜（ＬｕｆｆａｃｙｌｉｎｄｒｉｃａＲｏｅｍ．）为常食蔬菜，其果实和藤叶中含有多种生理活性的化学物质。我们从丝瓜叶中分离出１３个五环三萜类化合物，前文（１～３）已...